Professor Martin Rees, Astronomer Royal and Master of Trinity College Cambridge, will speak at the symposium entitled The State of the Universe.

He said: "When I first met Stephen Hawking we were both research students and it was thought that he might not live long enough even to finish his PhD degree.

"But, amazingly, he has reached the age of 70. Even mere survival would have been a medical marvel, but of course he hasn't merely survived.

"He has become arguably the most famous scientist in the world - acclaimed for his brilliant researches, for his best-selling books, and, above all, for his astonishing triumph over adversity."

Professor Brian Cox, known for his BBC science programmes and work on the Large Hadron Collider, also paid tribute to "a genius of Nobel Prize calibre".

He added: "In terms of popularising physics, I wouldn't be doing what I do now were it not for him.

"Stephen is one of only a handful of people in this field - whom I do not count myself among - who are genuine Nobel Prize contenders.

"He also realises that it is not just our job to 'do' physics but to explain it as it is something which fascinates people."

Prof Hawking is currently director of research at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, where he also founded the Centre for Theoretical Cosmology (CTC).

He previously held the Lucasian Professorship of Mathematics at Cambridge, a post once held by Isaac Newton.

The symposium is organised by the CTC in conjunction with technology company Intel.

In an interview ahead of his birthday, Prof Hawking told New Scientist that one thing remains a mystery to him - women.

Asked what he thinks most about during the day the physicist said: "Women. They are a complete mystery."

He also told the magazine his "biggest blunder" was thinking that information was destroyed in black holes.

"This was my biggest blunder, or at least my biggest blunder in science," he said.